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US 12,110,264 B2Granted
Process for producing urea and biuret
AssigneeCasale SA
InventorsLeonardo Marrone, Alberto Benedetti
Life of this patent
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Abstract
A process for the production of urea wherein: production of pure urea (U) includes the concentration of an aqueous urea solution (23) by crystallization; a urea crystallization purge aqueous phase (32) comprising urea, water and biuret, which is purged from the urea crystallization process, is used in a high-biuret urea processing section (34) for additional production of urea with a high content of biuret.
Claims13
A process for the production of urea, the process comprising:
- concentrating an aqueous urea solution by crystallization in a crystallization section to produce solid crystals of urea and a urea crystallization purge aqueous phase comprising urea, water and biuret;
- purging the urea crystallization purge aqueous phase from the crystallization process;
- and
- further processing at least a portion of said urea crystallization purge aqueous phase in a high-biuret urea processing section to produce a high-biuret urea in a solid form, wherein the high-biuret urea comprises at least 55% by weight of biuret;
- wherein urea is produced at a high pressure of synthesis in a urea synthesis section, obtaining a synthesis effluent;
- said effluent is processed in a recovery section at one or more pressure levels lower than the synthesis pressure to recover unconverted reagents which are recycled to the synthesis section, and said aqueous urea solution is obtained in the recovery section.
3 more elements
A method of modifying a urea plant, wherein:
- the plant includes a urea crystallization section arranged to produce solid urea by crystallization of an aqueous urea solution, to obtain solid crystals of urea and a crystallization aqueous phase comprising urea, water and biuret;
- the method including:
- adding a processing section to the plant, wherein the processing section is arranged to obtain, from said aqueous phase, a high-biuret urea in the form of a solid product made predominantly of biuret and urea;
- providing a line to feed part or all of the crystallization aqueous phase withdrawn from the urea crystallization section to the newly-installed processing section for the production of high-biuret urea;
- said modified urea plant comprising:
- a high-pressure urea synthesis section to obtain a synthesis effluent;
- a recovery section arranged to process said synthesis effluent at one or more pressure levels lower than the synthesis pressure to recover unconverted reagents and arranged to recycle said unconverted reagents to said urea synthesis section, and to obtain an aqueous urea solution;
- a urea crystallization section arranged to process said aqueous urea solution and to obtain solid crystals of urea and a urea crystallization purge aqueous phase comprising urea, water and biuret;
- a processing section and a line arranged to feed a said urea crystallization purge aqueous phase separated in the urea crystallization section to said processing section;
- the processing section being arranged to obtain, from said urea crystallization purge aqueous phase, a high-biuret urea in a solid form;
- wherein said processing section includes a crystallization section arranged to produce crystals containing biuret and a centrifuge arranged to separate the crystals from a crystallization mother liquor.
8 more elements
Dependencies are inferred from the claim text.